CGM-7 ACPD CRACK GROWTH MONITOR
Continuously variable frequency output from 10Hz to 500kHz in 1Hz
Advanced filtering capabilities with 3 user selectable ranges (and out).
10 pre-set gains built in. User selectable from 1000 to 30000.
Two channels as standard on all models.
High output currents up to 5 amps. Continuously variable in 1mA
User selectable offsets. Variable from -4v to +4v.
Resistive and inductive components simultaneously displayed.
Pre-amplifiers provided as standard for each channel for superior SNR.
Slow crack growth
Dynamic crack growth studies
Crack closure studies
Fatigue crack initiation
Stress corrosion testing
The CGM-7 is a modern microprocessor based instrument for measuring crack depth in metals undergoing
materials testing. Building on the success of the CGM-5R this unit improves upon the CGM-5R specification
by offering two channel operation, higher frequency and current outputs, full computer control and a variety of
It utilises the alternating current potential drop method (ACPD) which is an established technique covered by
the ASTM 647 standard. The technique involves passing an alternating current through the metal under test
and measuring the resultant voltage drop that is created across the specimen. The presence of a growing
defect will alter this voltage and by suitable calibration, a measure of the defect depth can be obtained.